How the race works and the way money is raise to boost the purse higher is explained on the Dirt Million Facebook page. There is a video in which Mansfield Motor Speedway track promoter Cody Sommers explains it all.
(Cody is the organizer of the Gateway Dirt Nationals)

Registration for the Dirt Million race on August 24th & 25th 2018 is now open.
Registration is now on line at this link - http://www.dirtmillion.com/registration.html
Drivers it is in your best interest to register as early as possible. Listen to the video to hear why and Cody will explain how this all works.